All size-flexible EC2 RIs provide the regional benefit, but the reverse is not always true.

In order for a Reserved Instance to provide the regional benefit, the following must be true:

It must be a Standard or Convertible Reserved Instance.

It must be in the active state.

It must not be tied to a specific Availability Zone.

In order for a Reserved Instance to be size flexible, it must meet the regional benefit criteria and also have a platform value of Linux/UNIX.

A Reserved Instance that provides the regional benefit applies to any instance in that region that matches the specifications of the Reserved Instance.

A size-flexible Reserved Instance applies all or part of its pricing benefit to any instance in the same instance family, regardless of Availability Zone or size. For example, a size-flexible Reserved Instance for a c4.large instance would apply to either a c4.large instance or two c4.medium instances. For a table that outlines the size footprints of various Reserved Instance sizes, see Understanding the Instance Size Footprint.